Process of cutting threads



E. DUCHESNE PROCESS OF CUTTING THREADS .Filed Nov. 11. 1924 Patented Oct. 25, 192?. I I

UNITED STATES PATENT OFFICE.

ERNEST DUCHESNE, OF SCHENECTADY, NEW YORK, ASSIGNOR TO LANDIS MACHINE COMPANY, OF WAYNESBORO, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

PROCESS OF CUTTING" THREADS.

.Appltcasion filed November 11, 1924. Serial No. 749,254.

My invention relates to an improved rocess for cutting tapered threads on stayolts and the like and it is an object of the same to render it possible to out such threads 6 without damaging the body of the bolt.

In former practice this has been almost an invariable consequence of any effort to cut tapered threads mechanically due to the fact that when the teeth at one end or side of the 1 chaser are brought into proper operative relation with the beginning of the tapered porticn the teeth at the other end or side of the chaser would engage with the body of the bolt and cut into it unless it was made 1 with a body of unduly small size or a thin neck.

Referring to the accompanying drawings which are made a part hereof and on which similar reference characters indicate similar parts,

Figure 1 is an end elevation of adie head carr ing hobbed cutters or chasers,

Figure 2, a fragmentary section showing the relation of the chasers to the work,

Figure 3, an end elevation of a die head provided with milled cutters or chasers,

Figure 4, a fragmentary section showing the relation of the milled chasers to the work,

Figure 5,'an end elevation of a die head equipped with tangential chasers of the Landis type, and

Figures 6 and 7 fragmentary sections showing the relation of said chasers to the work, Figure 7 showing a chaser having its back parallel to the teeth, and Figure 6 a chaser the back of which is not parallel to the teeth.

In Figure 1 of the drawings reference character 10 indicates the body of a hobbed cutter having chasers 11 mounted thereon as usual. In Figure 3 the body 13 carries milled chasers 14. In Figure 5 thebody 15 carries adjustable tangential chasers 16 held in chaser holders 17 as in the wellknown type of Landis thread cutting machines.

In each of Figures 2, 4, 6 and 7 thereis shown a stay-bolt having a body 18, a head 19 and a tapered portion 20 on which threads are to be formed. In each instance also the cutters are shown in the position assumed when the cutting has been partly performed, it being the purpose of my invention to begin the cutting at the larger end of the taper and work down to the smaller end. In previous practice it has uniformly been customary to begin at the smaller end and work toward the larger whereby the chaser teeth at the portion a (Fig. 2) of the chaser cut into and damage the shank or body of the bolt but by beginning such cutting at the larger end the thread is finished before the tooth (1 reaches the shank of the bolt.

It will be obvious from the illustration that my invention is not limited to any particular type of cutter it being only necessary that the controlling means for the cutters be so arranged as to diminish the size of the opening in the head as the cutting proceeds.

Having thus fully described my said invention, what I claim as new and desire to secure by Letters Patent is:

The process of cutting a thread on the tapered portion of a bolt having a cylindrical shank and a head tapering toward said shank consisting incutting threads from the larger end toward the cylindrical shank by means of a die head having a set of chasers that approach each other during such cutting operation, and withdrawing the chasers before engagement with the shank can occur, substantially as set forth.

In witness whereof, I have hereunto set my hand at Schenectady, New York, this 17th day of October, A. D. nineteen hundred and twenty-four.

ERNEST DUCHESNE. 

